What motivated the apostles' ministry in Jerusalem?
The apostles' ministry in Jerusalem was motivated by the hope that Israel would repent of crucifying their Messiah, so that Christ could return and establish His Kingdom. They knew they could not go beyond Israel's borders until Israel had her King, so they stayed, awaiting national repentance.
Les teaches that the twelve apostles were not derelict in staying in Jerusalem. According to the expectation from Matthew 28.28, they should have covered the Roman Empire within seven years, and even with the transportation of that day they could have reached much of the then-known world. But they remained in Jerusalem because they knew they could not go beyond the borders of Israel until Israel had her King. Their whole driving momentum was the hope that Israel would repent of the sin of having crucified their Messiah, so that Christ could turn and set up His Kingdom. Les also points to Zechariah 8:20, where God says through the prophet that "it shall yet come to pass," showing that what Israel was to do regarding the Gentiles and the rest of the world was still future, because Israel had not yet had the Kingdom.